SummaryThe goal of this project is to prepare in a deterministic way, and then to characterize, various entangled states of up to 25 individual atoms held in an array of optical tweezers. Such a system provides a new arena to explore quantum entangled states of a large number of particles. Entanglement is the existence of quantum correlations between different parts of a system, and it is recognized as an essential property that distinguishes the quantum and the classical worlds. It is also a resource in various areas of physics, such as quantum information processing, quantum metrology, correlated quantum systems and quantum simulation. In the proposed design, each site is individually addressable, which enables single atom manipulation and detection. This will provide the largest entangled state ever produced and fully characterized at the individual particle level. The experiment will be implemented by combining two crucial novel features, that I was able to demonstrate very recently: first, the manipulation of quantum bits written on long-lived hyperfine ground states of single ultra-cold atoms trapped in microscopic optical tweezers; second, the generation of entanglement by using the strong long-range interactions between Rydberg states. These interactions lead to the so-called dipole blockade , and enable the preparation of various classes of entangled states, such as states carrying only one excitation (W states), and states analogous to Schrödinger s cats (GHZ states). Finally, I will also explore strategies to protect these states against decoherence, developed in the framework of fault-tolerant and topological quantum computing. This project therefore combines an experimental challenge and the exploration of entanglement in a mesoscopic system.

The goal of this project is to prepare in a deterministic way, and then to characterize, various entangled states of up to 25 individual atoms held in an array of optical tweezers. Such a system provides a new arena to explore quantum entangled states of a large number of particles. Entanglement is the existence of quantum correlations between different parts of a system, and it is recognized as an essential property that distinguishes the quantum and the classical worlds. It is also a resource in various areas of physics, such as quantum information processing, quantum metrology, correlated quantum systems and quantum simulation. In the proposed design, each site is individually addressable, which enables single atom manipulation and detection. This will provide the largest entangled state ever produced and fully characterized at the individual particle level. The experiment will be implemented by combining two crucial novel features, that I was able to demonstrate very recently: first, the manipulation of quantum bits written on long-lived hyperfine ground states of single ultra-cold atoms trapped in microscopic optical tweezers; second, the generation of entanglement by using the strong long-range interactions between Rydberg states. These interactions lead to the so-called dipole blockade , and enable the preparation of various classes of entangled states, such as states carrying only one excitation (W states), and states analogous to Schrödinger s cats (GHZ states). Finally, I will also explore strategies to protect these states against decoherence, developed in the framework of fault-tolerant and topological quantum computing. This project therefore combines an experimental challenge and the exploration of entanglement in a mesoscopic system.

SummaryForests, of which globally 70% are managed, play a particularly important role in the global carbon cycle. Recently, forest management became a top priority on the agenda of the political negotiations to mitigate climate change because forest plantations may remove atmospheric CO2 and if used for energy production, the wood is a substitute for fossil fuel. However, this political imperative is at present running well ahead of the science required to deliver it. Despite the key implications of forest management on: 1) the carbon-energy-water balance, and 2) production, recreation and environmental protection, there are no integrated studies of its effects on the Earth s climate. The overall goal of DOFOCO is to quantify and understand the role of forest management in mitigating climate change. Specifically, I want to challenge the current focus on the carbon cycle and replace it with a total climate impact approach. Hence, the whole forest management spectrum ranging from short rotation coppice to old-growth forests will be analyzed for its effects on the water, energy and carbon cycles. Climate response of forest will be quantified by means of albedo, evapotranspiration, greenhouse gas sources and sinks and their resulting climate feedback mechanisms. The anticipated new quantitative results will be used to lay the foundations for a portfolio of management strategies which will sustain wood production while minimizing climate change impacts. DOFOCO is interdisciplinary and ground breaking because it brings together state-of-the art data and models from applied life and Earth system sciences; it will deliver the first quantitative insights into how forest management strategies can be linked to climate change mitigation.

Forests, of which globally 70% are managed, play a particularly important role in the global carbon cycle. Recently, forest management became a top priority on the agenda of the political negotiations to mitigate climate change because forest plantations may remove atmospheric CO2 and if used for energy production, the wood is a substitute for fossil fuel. However, this political imperative is at present running well ahead of the science required to deliver it. Despite the key implications of forest management on: 1) the carbon-energy-water balance, and 2) production, recreation and environmental protection, there are no integrated studies of its effects on the Earth s climate. The overall goal of DOFOCO is to quantify and understand the role of forest management in mitigating climate change. Specifically, I want to challenge the current focus on the carbon cycle and replace it with a total climate impact approach. Hence, the whole forest management spectrum ranging from short rotation coppice to old-growth forests will be analyzed for its effects on the water, energy and carbon cycles. Climate response of forest will be quantified by means of albedo, evapotranspiration, greenhouse gas sources and sinks and their resulting climate feedback mechanisms. The anticipated new quantitative results will be used to lay the foundations for a portfolio of management strategies which will sustain wood production while minimizing climate change impacts. DOFOCO is interdisciplinary and ground breaking because it brings together state-of-the art data and models from applied life and Earth system sciences; it will deliver the first quantitative insights into how forest management strategies can be linked to climate change mitigation.

Max ERC Funding

1 296 125 €

Duration

Start date: 2010-02-01, End date: 2015-10-31

Project acronymEXOEARTHS

ProjectEXtra-solar planets and stellar astrophysics: towards the detection of Other Earths

SummaryThe detection of more than 300 extrasolar planets orbiting other solar-like stars opened the window to a new field of astrophysics. Many projects to search for Earth-like planets are currently under way, using a huge battery of telescopes and instruments. New instrumentation is also being developed towards this goal for use in both ground- and space-based based facilities. Since planets come as an output of the star formation process, the study of the stars hosting planets is of great importance. The stellar-planet connection is strengthened by the fact that most of the exoplanets were discovered using a Doppler radial-velocity technique, where the gravitational influence of the planet on the star and not the planet itself is actually measured. This project aims at doing frontier research to explore i) in unique detail the stellar limitations of the radial-velocity technique, as well as ways of reducing them, having in mind the detection of Earth-like planets and ii) to develop and apply software packages aiming at the study of the properties of the planet-host stars, having in mind the full characterization of the newfound planets, as well as understanding planet formation processes. These goals will improve our capacity to detect, study, and characterize new very low mass extra-solar planets. EXOEarths further fits into the fact that I am currently Co-PI of the project for a new high-resolution ultra-stable spectrograph for the VLT. The results of this project are crucial to fully exploit this new instrument. They will be also of extreme importance to current state-of-the-art planet-search projects aiming at the discovery of other Earths, in particular those making use of the radial-velocity method.

The detection of more than 300 extrasolar planets orbiting other solar-like stars opened the window to a new field of astrophysics. Many projects to search for Earth-like planets are currently under way, using a huge battery of telescopes and instruments. New instrumentation is also being developed towards this goal for use in both ground- and space-based based facilities. Since planets come as an output of the star formation process, the study of the stars hosting planets is of great importance. The stellar-planet connection is strengthened by the fact that most of the exoplanets were discovered using a Doppler radial-velocity technique, where the gravitational influence of the planet on the star and not the planet itself is actually measured. This project aims at doing frontier research to explore i) in unique detail the stellar limitations of the radial-velocity technique, as well as ways of reducing them, having in mind the detection of Earth-like planets and ii) to develop and apply software packages aiming at the study of the properties of the planet-host stars, having in mind the full characterization of the newfound planets, as well as understanding planet formation processes. These goals will improve our capacity to detect, study, and characterize new very low mass extra-solar planets. EXOEarths further fits into the fact that I am currently Co-PI of the project for a new high-resolution ultra-stable spectrograph for the VLT. The results of this project are crucial to fully exploit this new instrument. They will be also of extreme importance to current state-of-the-art planet-search projects aiming at the discovery of other Earths, in particular those making use of the radial-velocity method.

Max ERC Funding

928 090 €

Duration

Start date: 2009-10-01, End date: 2014-12-31

Project acronymFRECQUAM

ProjectFrequency Combs Quantum Metrology

Researcher (PI)Nicolas Treps

Host Institution (HI)UNIVERSITE PIERRE ET MARIE CURIE - PARIS 6

Call DetailsStarting Grant (StG), PE2, ERC-2009-StG

SummaryOptical frequency combs are extraordinary tools for metrology which have been recently crowned by a Nobel prize: they have replaced complicated frequency chains to perform direct frequency and time measurements with much higher accuracy, which is now getting close to the quantum limit. However, quantum aspects of measurements performed with these sources have not yet been studied. This is the subject of this proposal. Based on model experiments such as space-time positioning, dispersion, velocity or frequency measurements, we propose to assess and reach experimentally ultimate limits derived from information theory in presence of quantum noise. We also propose to go beyond these limits using non-classical states. More specifically, we propose to fulfil the following objectives : &quot; Objective 1 : achieve the best absolute space-time positioning sensitivity ever using quantum optics techniques applied to frequency combs. &quot; Objective 2 : apply those techniques to other high sensitivity measurement such as dispersion, velocity or frequency metrology. &quot; Objective 3 : explore fundamental quantum physics effects in the lab with quantum frequency combs. These tasks will be performed by developing a quantum frequency comb factory, based on mode locked laser sources and parametric oscillators, whose conception is a research line in itself, and that would also be used for new quantum states generation such as macroscopic entanglement and multimode states.

Optical frequency combs are extraordinary tools for metrology which have been recently crowned by a Nobel prize: they have replaced complicated frequency chains to perform direct frequency and time measurements with much higher accuracy, which is now getting close to the quantum limit. However, quantum aspects of measurements performed with these sources have not yet been studied. This is the subject of this proposal. Based on model experiments such as space-time positioning, dispersion, velocity or frequency measurements, we propose to assess and reach experimentally ultimate limits derived from information theory in presence of quantum noise. We also propose to go beyond these limits using non-classical states. More specifically, we propose to fulfil the following objectives : &quot; Objective 1 : achieve the best absolute space-time positioning sensitivity ever using quantum optics techniques applied to frequency combs. &quot; Objective 2 : apply those techniques to other high sensitivity measurement such as dispersion, velocity or frequency metrology. &quot; Objective 3 : explore fundamental quantum physics effects in the lab with quantum frequency combs. These tasks will be performed by developing a quantum frequency comb factory, based on mode locked laser sources and parametric oscillators, whose conception is a research line in itself, and that would also be used for new quantum states generation such as macroscopic entanglement and multimode states.

SummaryUltraintense and ultrashort light pulses have a huge potential for applications, such as the production of very compact particle accelerators. Exploiting this potential requires pushing the characteristics of lasers beyond their present state-of-the-art performances. However, the laser technology used so far is approaching its limits, in particular because of the optical breakdown of conventional optical media. Overcoming these limits requires finding radically new approaches for optics at ultrahigh laser intensities. The idea of this proposal consists in developing optical elements based on plasmas, i.e. plasma optics . Since plasmas are already ionized, they can sustain electromagnetic fields of extremely large amplitude. They can thus be exploited to produce several key optical elements needed to manipulate e.g. shorten, convert in frequency, or even amplify- existing ultraintense lasers. To this end, two main physical processes are exploited: laser-excited Langmuir waves, and the Doppler effect associated to the relativistic motion of plasmas in ultraintense laser fields. This project would contribute to the conception of a system consisting in a chain of several plasma optics, placed at the output of a table-top laser, which would deliver few-optical-cycle long PetaWatt-class near-visible light pulses, as well as Terawatt-class attosecond pulses in the soft x-ray range. Such light sources would open exciting perspectives in Science and Technology. More fundamentally, this project will exploit the coherent light emission induced during relativistic laser-plasma interaction as a fine probe of the ultrafast plasma dynamic. This new type of diagnostic should lead to significant progresses in the understanding of laser-plasma interaction at extreme laser intensities.

Ultraintense and ultrashort light pulses have a huge potential for applications, such as the production of very compact particle accelerators. Exploiting this potential requires pushing the characteristics of lasers beyond their present state-of-the-art performances. However, the laser technology used so far is approaching its limits, in particular because of the optical breakdown of conventional optical media. Overcoming these limits requires finding radically new approaches for optics at ultrahigh laser intensities. The idea of this proposal consists in developing optical elements based on plasmas, i.e. plasma optics . Since plasmas are already ionized, they can sustain electromagnetic fields of extremely large amplitude. They can thus be exploited to produce several key optical elements needed to manipulate e.g. shorten, convert in frequency, or even amplify- existing ultraintense lasers. To this end, two main physical processes are exploited: laser-excited Langmuir waves, and the Doppler effect associated to the relativistic motion of plasmas in ultraintense laser fields. This project would contribute to the conception of a system consisting in a chain of several plasma optics, placed at the output of a table-top laser, which would deliver few-optical-cycle long PetaWatt-class near-visible light pulses, as well as Terawatt-class attosecond pulses in the soft x-ray range. Such light sources would open exciting perspectives in Science and Technology. More fundamentally, this project will exploit the coherent light emission induced during relativistic laser-plasma interaction as a fine probe of the ultrafast plasma dynamic. This new type of diagnostic should lead to significant progresses in the understanding of laser-plasma interaction at extreme laser intensities.

SummaryI intend to use string theory to understand gauge theories in four dimensions, both at strong and weak coupling. This includes describing strongly interacting gauge theories and their metastable vacua using their supergravity and string duals, as well as understanding gauge theories at intermediate coupling via integrability. It also includes using and developing new string-inspired twistor-space techniques to analyze QCD and N=1 amplitudes at one loop level. I also plan to thoroughly investigate the implications of string theory for the physics of black holes. In particular I want to construct and analyze black hole microstates -- smooth horizon-less solutions that are very similar to the black hole asymptotically, but differ from the black hole at the location of the horizon. Counting and understanding these microstates via the AdS-CFT correspondence will establish whether black holes should be thought of as ensembles of such microstate geometries.

I intend to use string theory to understand gauge theories in four dimensions, both at strong and weak coupling. This includes describing strongly interacting gauge theories and their metastable vacua using their supergravity and string duals, as well as understanding gauge theories at intermediate coupling via integrability. It also includes using and developing new string-inspired twistor-space techniques to analyze QCD and N=1 amplitudes at one loop level. I also plan to thoroughly investigate the implications of string theory for the physics of black holes. In particular I want to construct and analyze black hole microstates -- smooth horizon-less solutions that are very similar to the black hole asymptotically, but differ from the black hole at the location of the horizon. Counting and understanding these microstates via the AdS-CFT correspondence will establish whether black holes should be thought of as ensembles of such microstate geometries.

Max ERC Funding

652 500 €

Duration

Start date: 2010-01-01, End date: 2014-12-31

Project acronymUPGAL

ProjectUnderstanding the Physics of Galaxy Formation and Evolution at High Redshift

SummaryUnderstanding the processes regulating galaxy formation is a major open issue in observational cosmology. We now have a fairly detailed census of the diverse high-z galaxy populations, hence time is ripe for fundamental advances in understanding galaxy formation and evolution in the crucial first few billion years. This requires to observationally constrain and clarify the physical processes that operated at those early epochs. Thanks to a new galaxy selection technique that I recently introduced, I have been leading research projects that have now provided major new results on high redshift z~2 galaxies. These include molecular gas first seen in typical high-z galaxies; the major phase of star formation at very high rates; widespread presence of previously unknown Compton-thick AGNs inside massive galaxies; and the existence of evolved galaxy clusters containing X-ray emitting gas already at z~2. Building on the legacy of these discoveries and critical results, I ask for support to fund the establishment of a new research team to lead research aimed at exploring the physics of galaxy formation in the distant Universe. With three postdocs each year for a total of 5 years, we will pave new avenues towards understanding the relation between black holes and galaxies at the time of their major mass growth and assembly. In a full multiwavelength approach, by obtaining and using data from all major observational facilities (both in space and on the ground) we will aim to clarify the physical trigger of downsizing, catch AGN feedback in action and assess its role in galaxy transformations, along with the effects of the environment, gas accretion, star formation and merging in driving galaxy formation.

Understanding the processes regulating galaxy formation is a major open issue in observational cosmology. We now have a fairly detailed census of the diverse high-z galaxy populations, hence time is ripe for fundamental advances in understanding galaxy formation and evolution in the crucial first few billion years. This requires to observationally constrain and clarify the physical processes that operated at those early epochs. Thanks to a new galaxy selection technique that I recently introduced, I have been leading research projects that have now provided major new results on high redshift z~2 galaxies. These include molecular gas first seen in typical high-z galaxies; the major phase of star formation at very high rates; widespread presence of previously unknown Compton-thick AGNs inside massive galaxies; and the existence of evolved galaxy clusters containing X-ray emitting gas already at z~2. Building on the legacy of these discoveries and critical results, I ask for support to fund the establishment of a new research team to lead research aimed at exploring the physics of galaxy formation in the distant Universe. With three postdocs each year for a total of 5 years, we will pave new avenues towards understanding the relation between black holes and galaxies at the time of their major mass growth and assembly. In a full multiwavelength approach, by obtaining and using data from all major observational facilities (both in space and on the ground) we will aim to clarify the physical trigger of downsizing, catch AGN feedback in action and assess its role in galaxy transformations, along with the effects of the environment, gas accretion, star formation and merging in driving galaxy formation.